In Java. Modify the single server version of KnockKnock program so that the client and server take turns exchanging string messages (Simple Instant Messenger). SimpleIMProtocol replaces KnockKnockProtocol. Display a prompt to indicate whose turn it is to type a message.

KnockKnockProtocol code:

import java.net.*; import java.io.*; public class KnockKnockProtocol { private static final int WAITING = 0; private static final int SENTKNOCKKNOCK = 1; private static final int SENTCLUE = 2; private static final int ANOTHER = 3; private static final int NUMJOKES = 5; private int state = WAITING; private int currentJoke = 0; private String[] clues = { "Turnip", "Little Old Lady", "Atch", "Who", "Who" }; private String[] answers = { "Turnip the heat, it's cold in here!", "I didn't know you could yodel!", "Bless you!", "Is there an owl in here?", "Is there an echo in here?" }; public String processInput(String theInput) { String theOutput = null; if (state == WAITING) { theOutput = "Knock! Knock!"; state = SENTKNOCKKNOCK; } else if (state == SENTKNOCKKNOCK) { if (theInput.equalsIgnoreCase("Who's there?")) { theOutput = clues[currentJoke]; state = SENTCLUE; } else { theOutput = "You're supposed to say \"Who's there?\"! " + "Try again. Knock! Knock!"; } } else if (state == SENTCLUE) { if (theInput.equalsIgnoreCase(clues[currentJoke] + " who?")) { theOutput = answers[currentJoke] + " Want another? (y/n)"; state = ANOTHER; } else { theOutput = "You're supposed to say \"" + clues[currentJoke] + " who?\"" + "! Try again. Knock! Knock!"; state = SENTKNOCKKNOCK; } } else if (state == ANOTHER) { if (theInput.equalsIgnoreCase("y")) { theOutput = "Knock! Knock!"; if (currentJoke == (NUMJOKES - 1)) currentJoke = 0; else currentJoke++; state = SENTKNOCKKNOCK; } else { theOutput = "Bye."; state = WAITING; } } return theOutput; }